1. Field of the Invention
This invention relates to methods and means for mounting one element in circumferential relationship with another element in which either or both elements are non-metallic and in which lateral movement of the assembled elements relative to each other is prevented.
2. Description of the Prior Art
It is conventional to assemble one element in surrounding relationship to another element as, for example, when attaching a flange to a cylinder or a wheel to a bushing, by means of a pressed fit. This method is comparatively inexpensive and works well when both the inner and outer elements are metallic. When the interference fit is properly selected, a bushing or other type metallic bearing can be pressed within the hub of a wheel, pulley or sheave and the interference fit will suffice to prevent the bushing from moving axially with respect to the hub when mounted on a shaft for rotation. However, when either the bearing or the hub are made from a non-metallic material such as a plastic, a pressed fit is not always adequate to secure the one element to the other. If one element is plastic and the other is metal this is due, in part, to the lower modulus of plastics as compared to metal as well as the large difference in the coefficient of thermal expansion between plastics and metals which, under varying temperature conditions, may cause the interference fit to loosen. An interference fit may also loosen in time when one or both of the elements is made from plastic since most plastics are subject to cold flow and creep.
Plates mounted on either side of the assemblage may be secured by threaded bolts to prevent the two elements from moving laterally with respect to each other but this may be objectionable due to the increased size, weight, and cost of the assemblage.
Accordingly, it is an object of this invention to provide methods and means whereby one element may be mounted in surrounding relationship to another element in a manner in which the elements are prevented from moving laterally with respect to each other.
Another object of this invention is to provide methods and means whereby the lateral movement between an outer element mounted in surrounding relationship to an inner part may be prevented under conditions of use, particularly when one of the elements is made of plastic, but which permits the parts to be non-destructively separated if desired.
Briefly these and other objects of this invention are achieved by providing complementary grooves on the OD of the inner element and the ID of the outer element to define, when the elements are assembled, an annular channel into which a locking member can be inserted. In one embodiment of this invention, a radial passage is drilled through one element to provide access to the channel and, after assembly, round balls having a diameter slightly smaller than the diameter of the channel are fed into the channel. After the balls have been inserted, the drilled passageway is capped to prevent the balls from coming out. Depending upon the number of balls used and their modulus, the resistance to lateral movement of the one element relative to the other element can be controlled so that, if desired, the resistance to lateral movement may be sufficient to restrain motion during intended conditions of use, but may yield to permit nondestructive separation of the two elements when a sufficient force is provided.
This invention finds particular utility for mounting a rim or a flange on a cylindrical body or when inserting a bushing into a device such as a wheel, gear or pulley in preparation for mounting the device on a shaft for rotation.